Which of the following is the GREATEST security concern with respect to BYOD?

Filtering sensitive data at geographic boundaries is a data residency and sovereignty concern that applies broadly to network and cloud architecture design, not a security issue specific to the BYOD model.

Removing bottlenecks in data transmission paths is a network performance and capacity planning concern, not a security risk introduced by BYOD.

The transfer of corporate data onto managed corporate mobile devices represents a controlled, policy-governed operation; corporate devices are enrolled in MDM and subject to organizational security controls unlike personal BYOD devices.

BYOD devices are personal property and often lack enforced data loss prevention, MDM policies, or access controls, which means corporate data can freely migrate off the network through personal cloud storage, messaging apps, or unsanctioned channels - creating an uncontrolled data exfiltration risk that is the defining security challenge of BYOD.